engleski

DESIGN AND 3D PRINTING OF A SOLID-LIQUID MILLISEPARATOR

Additive manufacturing allows production of the complex shapes and geometries from one part, unlike other conventional methods that require multi-component devices to achieve the accuracy and dimensions presented here. Additive manufacturing was used to produce milliseparators with spiral internal geometry. The technologies used were stereolithography (SLA) and fused filament fabrication (FFF). The SLA 3D printer used was Formlabs Form 2 and the material was Clear V4 (acrylate resin). The FFF 3D printer used was Zortrax M200 and the material PET-G (glycol-modified polyethylene terephthalate). The models of the milliseparator were designed in computer aided design (CAD) software Autodesk Fusion 360. The models were designed in several versions with 2 mm and 3 mm channel diameters and with 5 and 6 spiral revolutions. The milliseparators had one inlet and two outlets (Fig. 1). After the milliseparators were successfully manufactured on the 3D printers (Fig. 2), they were used to separate water-powder mixtures. The powders used were quartz sand (Samoborka D. D.), nano CaCO3 (Schaefer Kalk GmbH & Co. KG.), and baby powder (Nivea, Beiersdorf AG). The mixtures were prepared with 0.33 wt% of the powder in the water, and for the baby powder, 10 wt% of isopropyl alcohol was added to water to improve dispersion. The mixture was mixed on a magnetic stirrer (IKA RCT Digital) and pumped through the milliseparator using a peristaltic pump (FlexiPump Interscience). The flow rates used were 150 mL/min, 200 mL/min, and 250 mL/min. Prior to separation, all powders were characterized by laser diffraction, sieve analysis, and scanning electron microscopy (SEM). After the separation was performed, separator efficiency was determined by weighing the dried powder samples from each outlet and laser diffraction was performed to determine if there was a size difference in powder particles between the outlets. The milliseparator with a channel diameter of 2 mm was successfully 3D printed, but was not functional because powders clogged the channels. Therefore, only separators with a channel diameter of 3 mm were used. The milliseparator manufactured with FFF technology was also inadequate because the interlayer adhesion was poor, which caused the mixture to leak through the body of the separator. The milliseparator made by the SLA technology, with a channel diameter of 3 mm, proved to be adequate and functional for the powder mixture separation. Quartz sand caused non-uniform volume flow through the outlets at all flow rates, while CaCO3 and baby powder had the same volume flow at all flow rates. The results indicate the best separation for the quartz sand and CaCO3 occurred at a flow rate of 250 mL/min according to the mass analysis and the best separation for baby powder occurred at a flow rate of 150 mL/min. Laser diffraction analysis for quartz sand at a flow rate of 250 mL/min shows mode values of 282 µm and 447 µm for each outlet. For baby powder at a flow rate of 150 mL/min, the laser diffraction analysis shows mode values of 35 µm and 28 µm for each outlet. It can be concluded that additive manufacturing can be used to successfully produce milliseparators and use them for the separation of solid-liquid mixtures. In addition, further modifications such as the shape of the cross- section, the number of spiral revolutions or the flow rate should be investigated to improve the separation efficiency.

Additive manufacturing ; 3D printing ; milliseparator

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